Thermoplastics are compositions which can be molded or otherwise shaped and reprocessed at temperatures above their melting or softening point. Thermoplastic elastomers (elastoplastics) are materials which exhibit both thermoplastic and elastomeric properties, i.e., the materials process as thermoplastics but have physical properties like elastomers. Shaped articles may be formed from thermoplastic elastomers by extrusion, injection molding or compression molding without the time-consuming cure step required with conventional vulcanizates. Elimination of the time required to effect vulcanization provides significant manufacturing advantages. Further, thermoplastic elastomers can be reprocessed without the need for reclaiming, and, in addition, many thermoplastics can be thermally welded.
Moldable thermoplastic compositions of nylon and cured rubber containing high proportions of nylon prepared from scrap tire cord material are known but such compositions are rigid nonelastomeric materials of high stiffness and low elongation (Elgin, U.S. Pat. No. 3,468,794). Moldable thermoplastic compositions of nylon and curable rubber containing high proportions of rubber are known which compositions are cured in a mold (British Pat. Nos. 866,479 and 1,190,049). These compositions, of course, are not thermoplastic after cure and not remoldable as thermoplastic. Elastoplastic compositions of nylon and rubber containing phenol plasticizers are described in French Pat. No. 1,592,857. Resorcinol and hydroquinone both dihydric phenols are illustrated as plasticizers. The patent indicates that the presence of phenolic plasticizer is essential for obtaining thermoplasticity.